The present invention relates to an engine cylinder head gasket utilizing a retaining ring and a spring energized seal disposed within an annular U-shaped flange adjacent a gasket body.
A cylinder head gasket bears a clamping load from a bolted connection between a cylinder head and an engine block and relies upon that load to provide a seal against the sealing elements of the gasket. The gasket includes a combustion seal to prevent the leakage of combustion gases during engine operation.
Known gaskets use any of several types of combustion seal rings. One type, known as a yieldable combustion seal ring, is essentially comprised of a wire having a generally circular cross-sectional area. A clamping force applied to such a ring is concentrated at the point of contact, deforming the ring's circumference to effectively seal out combustion gases. This type of seal ring, however, is subject to thermal crushing which produces additional plastic deformation that tends to occur under high temperature operation during the life of the ring.
Other known gaskets use a spring energized seal. The spring energized seal extends about the cylinder bore and defines an annulus. The seal has a generally circular cross-section and comprises both an outer jacket and an inner spring. As with the yieldable combustion seal ring, a clamping force applied to such a ring is concentrated at the point of contact to seal out combustion gases. The spring energized seal requires only a low load before sealing out combustion gases, which is of particular importance in a cold engine start up condition. Such a spring energized seal, however, is also subject to thermal crushing. Further, the spring energized seal tends to roll or pivot about its annular axis in use, leading to undesirable fatigue under certain circumstances.